Ensheathing cells: Large scale purification from adult olfactory bulb, freeze-preservation and migration of transplanted cells in adult brain

Abstract

Regenerating nerve fiber sprouts enveloped by olfactory bulb (OB) ensheathing cells (ECs) seem to escape the inhibitory influence of gliotic tissue. Accordingly, these cells may be useful for general repair of injured CNS. Relatively large numbers of ECs could be purified from confluent cultures of adult rat olfactory bulb using immunomagnetic beads. Viable ECs could be cultured and purified in good yield from OB dissected up to 18 h post-mortem. Purified ECs could be stored frozen at - 75°C for at least G months, while maintaining 95% viability. ECs labelled with the fluorescent cell-linker PKH-26 neither shed the label nor exchanged it with other cells. The migration of labelled ECs transplanted to adult hippocampus was examined at intervals ranging from 3 h to 30 days. Active migration from the injection site was first observed 4 days after transplantation, when ECs appeared intercalated between the neurons of the hippocampal and dentate cell layers. Some ECs remained in that location after 30 days but, at that time, the olfactory glial cells could be observed in loci as distant and diverse as the laterodorsal thalamic nuclei, internal capsule, arcuate nucleus, cerebral aqueduct walls and choroid plexus. ECs seemed to have preferences for the dentate hilus, the pyramidal and granular cell layers, choroid plexus, blood vessels and putative peptidergic loci.